基于多级微反射镜的时空联合调制傅里叶变换成像光谱仪:原理及数据处理

摘要

This manuscript introduces the principle and data processing method of a stepped mirror based tem-porally and spatially modulated imaging Fourier transform spectrometer .The instrument substitutes the mov-ing mirror ,which is widely used in a Michelson interferometer ,with a stepped mirror to realize static interfer-ence .A scanning mirror is placed in front of the first imaging system to make the target image on different sub-mirrors to get different optical path differences .Light emitted from the target propagate through the scan-ning mirror and the first imaging system to focus on the stepped mirror and the plane mirror to form two pri-mary images .The primary images are then reflected by the stepped and plane mirrors to propagate through the second imaging system and finally image on the detector .Since there are optical path differences between the stepped mirror and the plane mirror ,the image captured by the detector would have the two-dimensional spa-tial and one-dimensional spectral information of the target .The scanning interval of the scanning mirror is set to be 0.095° according to the parameters of the stepped mirror and the optical system .Image stitching and spectrum reconstruction are done using the experimental data cube .A polar Hough transform based image cut-ting method is proposed to deal with the sub-mirror width difference problem in image cutting .To mitigate the discontinuity line effect in the panorama ,the image is transformed to the HSI space to adjust its intensity .Af-ter interferogram dimension reduction ,direct current offset removal ,interferogram addressing ,apodization , phase correction ,Fourier transform and spectral resolution enhancement ,the spectrum is reconstructed and its resolution is 194 cm -1 ,which is better than the designed value (250 cm -1 ) .%介绍了一种基于多级阶梯微反射镜的时空联合调制傅里叶变换成像光谱仪的原理及数据处理方法.仪器利用一块多级阶梯微反射镜取代传统迈克尔逊干涉仪中的动镜以实现静态干涉,通过摆镜扫描使目标物体成像在不同的子阶梯反射面上从而获得目标物体不同光程差的干涉信息.某一时刻,目标物体经摆镜与前置成像系统后在平面镜与多级阶梯微反射镜上形成两个一次像点,两个一次像点被平面镜和多级阶梯微反射镜反射之后经后置成像系统最终成像在探测器焦平面上.平面镜与多级阶梯微反射镜之间的高度差会使到达探测器的两束光的光程差不同,因此探测器焦平面上可以获得目标物体的二维空间信息及一维干涉信息.根据多级阶梯微反射镜参数及光学系统设计参数计算得到摆镜步进角度为0.095°.利用实验获得的三维数据立方体进行了图像拼接与光谱复原.针对子阶梯反射镜存在宽度差异的问题,提出了一种基于极坐标霍夫变换的图像分割方法.为缓解拼接全景图中的间断线效应,将图像变换到HSI颜色空间并插值拟合其亮度分量后再变换回原空间.对拼接后的干涉图像进行了降维、去直流、寻址、切趾、相位校正、傅里叶变换及光谱分辨率增强等处理,完成了光谱复原工作.复原光谱分辨率为194 cm-1,优于设计指标(250 cm-1).